In public or private communication networks, communication systems communicate using standardized signaling procedures (e.g. signaling procedure no. 7) or specific signaling procedures for private communication networks (e.g. Cornet, of the firm Siemens). In private communication networks in particular, the signaling and message information to be exchanged are transmitted via fixed connections (e.g. a signaling procedure no. 7 fixed connection), whereby messages are inserted into the signaling information, by means of which messages the communication systems are controlled with regard to switching. For takeover and preparation of messages, at least one internal message interface is provided in the communication systems, whereby the formats of the messages or message elements transmitted via the internal message interface can deviate dependent on the release, i.e. on the degree of updating of the respective communication system. The information contents of the messages remain equal, however. These different formats result in the communication system in particular given extensive expansions for controlling additional performance features, whereby the program-oriented changes arc displayed in the communication system by means of an updating information or a release information.